1. Field of the Invention
The present invention relates to the treatment of liquid materials containing compounds or species which are apt to produce solid waste substances, or pollutants, as a result of certain physico/chemical operations being performed thereon, and, more especially, to the treatment of waste waters containing inorganic and/or organic salts, certain of which having low melting points, such as sulfides, sulfates, chlorides, and the like.
2. Description of the Prior Art
It is well known to this art that the purification of waste waters is both difficult and complex, and, accordingly, the state of the art is replete with various proposed solutions to this problem.
Thus, physico/chemical methods have been proposed, such as those featured in French Pat. No. 2,320,268. Same are characterized in that the waste water, adjusted to a pH below 7 and having a temperature ranging from 20.degree. to 200.degree. C., is contacted with pure technical oxygen at a pressure ranging from normal pressure to 20 bars, until the sulfide therein is converted into thiosulfates; then the thiosulfates are converted to sulfates with technical oxygen, at a pH of from 0 to 5, or from 0 to 8 in the case of waste water containing only sulfates, at temperatures from 20.degree. to 200.degree. C., at pressures of up to 20 bars, and optionally in the presence of suitable catalysts.
However, the mere characterization of such a process bares its complexity. French Pat. No. 2,306,610, therefore, proposes to alternatively subject the water to simultaneous spraying conjointly with an oxidizing heat treatment. In this particular process, contacting and treatment may be carried out in a reactor/contactor as described in French Pat. No. 2,257,326 [corresponding to Prudhon et al application Ser. No. 916,477, filed June 19, 1978, abandoned, a continuation of Ser. No. 770,802, filed Apr. 19, 1977 (now abandoned), itself a continuation of Ser. No. 479,774, filed June 17, 1974 (also abandoned)], according to which at least one fluid is charged into the depression zone of a helical flow of a second fluid travelling under much greater momentum.
This method, nonetheless, has not proved sufficiently reliable industrially for this particular purpose, in view of the possible variation in the concentration of sulfur derivatives found in the process effluent.
Deposits too have been found to form in the collecting vessel.
This difficulty is thought to be due particularly to the presence of polysulfides. Though these have been known for a long time, having been described by Scheele as early as 1777, same generally reflect the presence of a mixture of constituents. Serious need therefore exists in this art for a treatment which can eliminate these objectionable compounds and possibly yet others. Also compare U.S. Pat. Nos. 3,758,081, 4,086,099, 4,124,353, 4,257,339, 4,263,234, 4,265,702 and 4,267,131, assigned to the assignee hereof and hereby expressly incorporated by reference.